how do I save and open SPSS files?

I have downloaded SPSS on my macbook and the first week I could work with it and save files. But the last days I can use SPSS for statistics but I can’t save my files not in save, ups or svp. When I save it saving with another file name is asked. If I do so and later want to retrieve it the file is empty. What do I wrong or is my license not correct anymore? That is strange after so little days.